Implantable medical devices are used in a variety of applications. One such medical application includes the monitoring of electrical impulses on the surface of a patient's brain. Tracking electrical activity of the brain is useful in conjunction with the treatment and/or diagnosis of certain medical conditions, such as epilepsy. Exemplary electrodes for contacting the brain are disclosed in U.S. Pat. Nos. 4,903,702 and 5,044,368, which are incorporated herein by reference.
In one technique, electrodes are implanted within the cranium in contact with the patient's brain. To position the electrodes, the surgeon typically forms a hole in the patient's skull for accessing selected tissue. One or more electrodes are positioned on the patient's brain for monitoring its electrical activity. After the electrodes are placed at the desired location, they must be coupled to a remote monitoring device which analyzes the data from the probes. A lead extends from the electrode to provide a signal pathway to the remote monitoring device.
In some procedures used to connect a terminal end of the probe lead to an external mating terminal, a trocar is tunneled under the patient's scalp for a predetermined distance after which it exits the scalp. The terminal end of the electrode lead is then threaded through a passageway in the trocar so that the terminal can be connected to a corresponding mating terminal of a lead coupled to the remote monitoring device.
During this procedure, the exposed terminal of the electrode lead becomes covered with bodily tissue and fluid as it passes through the trocar. Exposure to bodily substances can impair the integrity of an electrical connection between the terminal end of the eleectrode lead and the mating terminal of the remote device lead, which provides a signal path to the remote monitoring device. Due to the relatively high level of sensitivity that is required for accurate detection of signals generated by the brain, any attenuation or interference with the signals from the electrode can render the resulting data useless and/or misleading.
It would, therefore, be desirable to provide a system that is able to preserve the sensitivity of the electrode contacts during implantation within the body.